Many display systems use spatial light modulators such as liquid crystal display panels (LCDs) or digital mircomirror devices (DMD™) having a large number of pixel elements (on the order of one million or more) to create images. The spatial light modulator is illuminated by a light source and the position of the pixels are controlled so that light striking selected ones of the pixel elements is reflected to a display surface or screen to generate an image.
Conventional optics include a “integrator” element or light tunnel and relay optics for forming a rectangular-shaped image used to illuminate a rectangular-shaped active area of a spatial light modulator, such as for example, a DMD™. The relay optics form an image of the “integrator” output at the modulator. However, the rectangular-shaped illuminating image used by these conventional optics arrive at the spatial light modulator at an oblique angle of about 24° to 26°. Such an oblique illumination angle results in a distorted and uneven focus of the illuminating image onto the spatial light modulator. Consequently, when using conventional optics the illuminating image is significantly oversized to assure that portions of the active area of the spatial light modulator are evenly illuminated. The oversized illumination image wastes light and often causes other problems when non-active portions of the spatial light modulator are illuminated. Therefore, it would be advantageous to adjust the shape of the illuminating image to better conform to the shape of the active area of the spatial light modulator.